The effectiveness of Motivational interviewing (MI) has been well studied for many years; however, only in the last four years has research examined client speech during a therapy session, how this speech is affected by the clinician's use of MI, and how this speech affects the client's alcohol and other drug (AOD) use. Specifically, these studies have focused on the amount of client change talk (CT) that occurs during a session and how CT and therapist use of MI can affect AOD use. Change talk is defined as a client talking about the benefits of change, hope or optimism around change, or unhappiness with his/her behavior. Research on CT has been conducted predominantly with young adults and adults in individual-based sessions. Few studies have examined CT for adolescents and only one published study has examined CT for adolescents in a group setting. Because the group format is commonly used with teens in AOD treatment settings, it is important to understand how MI delivered in a group-based setting may affect adolescent change talk and how CT may subsequently affect use. This information is crucial to move the field forward and can help practitioners improve AOD group treatment for youth. This study will address this gap in the literature by adapting the SCOPE (Sequential Code for Observing Process Exchanges) for use in the group setting. All data have been collected as part of R01DA019938, Brief Substance Use Intervention for Youth in Teen Court so work can begin immediately. The specific aims of this R21 developmental/exploratory study are to: Aim 1. Make adaptations to SCOPE, as needed, to code CT in an adolescent group setting and demonstrate our ability to identify CT through estimates of inter-rater agreement in our MI groups. Aim 2. Examine peer responses to CT for each group session, and the association of CT with group facilitator language using sequential analysis methods. Aim 3. Conduct within-session analyses of how a) overall CT may affect AOD outcomes and b) how specific subtypes of CT (i.e., desire, ability, need, commitment) may be associated with AOD outcomes employing state of the art statistical methods (such as multiple membership multilevel models). Aim 4. Investigate the trajectories of CT across group sessions to determine if these are associated with AOD outcomes by examining the temporal occurrence of CT; for example, is it more important to have higher levels of CT at initial group sessions versus later group sessions? Using state of the art statistical techniques, this study will be able to take an important first look at the adolescet group process among at-risk youth and examine the effects of this process on individual adolescents' subsequent AOD use. Our findings will aid understanding of procedures to improve group therapy for at-risk adolescents with AOD problems.